Hydrant cap leak detector with oriented sensor

ABSTRACT

A nozzle cap includes a cap body defining a cap axis, the cap body defining a circumferential wall extending circumferentially around the cap axis; and a vibration sensor including a shaft, the shaft defining a first end and a second end, the first end attached to the circumferential wall, the cap axis positioned closer to the second end than to the first end.

REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No. 17/079,642, filed Oct. 26, 2020, which is a divisional of U.S. application Ser. No. 16/121,136, filed Sep. 4, 2018, which issued into U.S. Pat. No. 10,859,462 on Dec. 8, 2020, each of which is hereby specifically incorporated by reference herein in its entirety.

TECHNICAL FIELD

This disclosure relates to fire hydrants. More specifically, this disclosure relates to a vibration sensor for detecting leaks in a water system connected to a fire hydrant.

BACKGROUND

Fire hydrants are commonly connected to fluid systems, such as municipal water infrastructure systems and water mains, through stand pipes. Because these fluid systems are typically partially or entirely located underground, it can be difficult to detect leaks within the fluid systems. Additionally, it can be difficult to access these fluid systems for monitoring. Fire hydrants can provide convenient above-ground access to the fluid systems. Leaks within the fluid systems can send vibrations through the fluid system and up stand pipes to the fire hydrants. These vibrations propagating through the stand pipes and fire hydrants can be monitored to detect leaks within the connected fluid system. However, fire hydrants can be subjected to other sources of vibration such as wind, rain, ambient noise from loud passing vehicles, or direct contact such as pedestrians bumping into fire hydrants or bicyclists leaning their bicycles against fire hydrants. These sources of background noise can trigger false alarms or make it more difficult for a potential leak to be detected.

SUMMARY

It is to be understood that this summary is not an extensive overview of the disclosure. This summary is exemplary and not restrictive, and it is intended to neither identify key or critical elements of the disclosure nor delineate the scope thereof. The sole purpose of this summary is to explain and exemplify certain concepts of the disclosure as an introduction to the following complete and extensive detailed description.

Disclosed is a nozzle cap comprising a cap body defining a cap axis, the cap body defining a circumferential wall extending circumferentially around the cap axis; and a vibration sensor comprising a shaft, the shaft defining a first end and a second end, the first end attached to the circumferential wall, the cap axis positioned closer to the second end than to the first end.

Also disclosed is a hydrant assembly comprising a fire hydrant comprising a barrel and a nozzle extending outwards from the barrel; and a nozzle cap comprising a cap body mounted on the nozzle, the cap body defining a cap axis, the cap body defining a circumferential wall extending circumferentially around the cap axis; and a vibration sensor comprising a shaft, the shaft defining a first end and a second end, the first end attached to the circumferential wall, the cap axis positioned closer to the second end than to the first end.

Various implementations described in the present disclosure may include additional systems, methods, features, and advantages, which may not necessarily be expressly disclosed herein but will be apparent to one of ordinary skill in the art upon examination of the following detailed description and accompanying drawings. It is intended that all such systems, methods, features, and advantages be included within the present disclosure and protected by the accompanying claims. The features and advantages of such implementations may be realized and obtained by means of the systems, methods, features particularly pointed out in the appended claims. These and other features will become more fully apparent from the following description and appended claims, or may be learned by the practice of such exemplary implementations as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and components of the following figures are illustrated to emphasize the general principles of the present disclosure. The drawings are not necessarily drawn to scale. Corresponding features and components throughout the figures may be designated by matching reference characters for the sake of consistency and clarity.

FIG. 1 is a perspective view of a hydrant assembly in accordance with one aspect of the present disclosure.

FIG. 2 is a perspective rear view of a nozzle cap of the hydrant assembly of FIG. 1.

FIG. 3 is a front view of the nozzle cap of FIG. 2 shown with a cap cover 280 of the nozzle cap removed.

FIG. 4 is a perspective view of one example aspect of a vibration sensor in accordance with one aspect of the present disclosure.

FIG. 5 is a front detail view of the hydrant assembly of FIG. 1 focusing on the nozzle cap with the cap cover shown in transparency and the underlying components shown in dashed lines.

FIG. 6 is a front detail view of the hydrant assembly of FIG. 1 focusing on the nozzle the nozzle cap, which demonstrates various potential positions for the vibration sensor of FIG. 4.

FIG. 7 is a cross-sectional side view of a barrel and the nozzle cap of FIG. 1 taken along line 7-7 shown in FIG. 6.

DETAILED DESCRIPTION

The present disclosure can be understood more readily by reference to the following detailed description, examples, drawings, and claims, and the previous and following description. However, before the present devices, systems, and/or methods are disclosed and described, it is to be understood that this disclosure is not limited to the specific devices, systems, and/or methods disclosed unless otherwise specified, and, as such, can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

The following description is provided as an enabling teaching of the present devices, systems, and/or methods in its best, currently known aspect. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made to the various aspects of the present devices, systems, and/or methods described herein, while still obtaining the beneficial results of the present disclosure. It will also be apparent that some of the desired benefits of the present disclosure can be obtained by selecting some of the features of the present disclosure without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations to the present disclosure are possible and can even be desirable in certain circumstances and are a part of the present disclosure. Thus, the following description is provided as illustrative of the principles of the present disclosure and not in limitation thereof.

As used throughout, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “an element” can include two or more such elements unless the context indicates otherwise.

Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

For purposes of the current disclosure, a material property or dimension measuring about X or substantially X on a particular measurement scale measures within a range between X plus an industry-standard upper tolerance for the specified measurement and X minus an industry-standard lower tolerance for the specified measurement. Because tolerances can vary between different materials, processes and between different models, the tolerance for a particular measurement of a particular component can fall within a range of tolerances.

As used herein, the terms “optional” or “optionally” mean that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

The word “or” as used herein means any one member of a particular list and also includes any combination of members of that list. Further, one should note that conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain aspects include, while other aspects do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more particular aspects or that one or more particular aspects necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular aspect.

Disclosed are components that can be used to perform the disclosed methods and systems. These and other components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutation of these may not be explicitly disclosed, each is specifically contemplated and described herein, for all methods and systems. This applies to all aspects of this application including, but not limited to, steps in disclosed methods. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific aspect or combination of aspects of the disclosed methods.

Disclosed is a hydrant assembly and associated methods, systems, devices, and various apparatus. The hydrant assembly can comprise a fire hydrant and a vibration sensor. It would be understood by one of skill in the art that the disclosed hydrant assembly is described in but a few exemplary aspects among many. No particular terminology or description should be considered limiting on the disclosure or the scope of any claims issuing therefrom.

FIG. 1 is a perspective view of a hydrant assembly 100 comprising a fire hydrant 110 and a vibration sensor 380 (shown in FIG. 3) in accordance with one aspect of the present disclosure. The fire hydrant 110 can comprise a barrel 120, a nozzle cap 150, and a bonnet 180. The barrel 120 can define a top barrel end 122 and a bottom barrel end 124 disposed opposite from the top barrel end 122. The barrel 120 can be substantially tubular, and the barrel 120 can define a barrel axis 101 extending from the top barrel end 122 to the bottom barrel end 124. In the present aspect, the barrel axis 101 can be substantially vertically aligned wherein the barrel axis 101 is aligned with the force of gravity.

The barrel 120 can comprise a top flange 126 disposed at the top barrel end 122 and a base flange 128 disposed at the bottom barrel end 124. The base flange 128 can be fastened to a stand pipe flange 199 of a stand pipe 198 of a fluid system (not shown), such as a water main for example and without limitation. The base flange 128 can be fastened to the stand pipe flange 199 by a plurality of fasteners 130. A bonnet flange 182 of the bonnet 180 can be attached to the top flange 126 of the barrel 120, such as with a plurality of fasteners (not shown) similar to the fasteners 130. The bonnet 180 can comprise an operation nut 184, or “op nut”, which can be rotated to open and close a main valve (not shown) positioned at the bottom barrel end 124 or below in the stand pipe 198 in order to respectively supply or cut off pressurized water flow to the fire hydrant 110.

The barrel 120 can define one or more nozzles 140 a,b. The nozzle cap 150 can be screwed onto the nozzle 140 a to seal the nozzle 140 a. With the nozzle cap 150 sealing the nozzle 140 a, pressurized water cannot escape through the nozzle 140 a when the main valve (not shown) is in an open position. The nozzle cap 150 can define a cap nut 152 which can be turned, such as with a wrench, to tighten or loosen the nozzle cap 150 on the nozzle 140 a.

FIG. 2 is a perspective rear view of the nozzle cap 150 of the fire hydrant 110 of FIG. 1. The nozzle cap 150 can comprise a cap body 210 and a cap cover 280. The cap body 210 can define a first body end 212 and a second body end 214 disposed opposite from the first body end 212. The cap cover 280 can be attached to the first body end 212 of the cap body 210. The cap body 210 can define a threaded bore 216 extending into the cap body 210 from the second body end 214 to an inner wall 220 of the cap body 210. The threaded bore 216 can define a cap axis 201 of the cap body 210, and the cap axis 201 can extend from the first body end 212 to the second body end 214.

The threaded bore 216 can define internal threading 218, and the threaded bore 216 can be screwed onto the nozzle 140 a (shown in FIG. 1) to mount the nozzle cap 150 on the nozzle 140 a by rotating the nozzle cap 150 about the cap axis 201. In the present aspect, the internal threading 218 can be straight threading that does not taper from the second body end 214 towards the inner wall 220. In other aspects, the internal threading 218 can be tapered threading that tapers from the second body end 214 towards the inner wall 220. A gasket 222 can be positioned adjacent to the inner wall 220, and the gasket 222 can be configured to form a seal with the nozzle 140 a (shown in FIG. 1) when the nozzle cap 150 is screwed onto the nozzle 140 a in a sealed position. As described below with respect to FIGS. 6 and 7, the gasket 222 can be selected based on its thickness, measured axially along the cap axis 201, to alter a rotational indexing of the nozzle cap 150 relative to the nozzle 140 a.

FIG. 3 is a front view of the nozzle cap 150 of FIG. 1 with the cap cover 280 (shown in FIG. 2) removed from the cap body 210. The cap body 210 can define a cavity 310 extending inwards into the cap body 210 from the first body end 212 to the inner wall 220. In the present aspect, the cavity 310 can extend axially inward relative to the cap axis 201, shown extending out of the page. The inner wall 220 can separate the cavity 310 from the threaded bore 216 (shown in FIG. 2). The cap body 210 can define a circumferential wall 312 which partially encloses the cavity 310 and extends circumferentially around the cavity 310 relative to the cap axis 201. A cavity opening 313 to the cavity 310 can be defined at the first body end 212, and a cavity gasket 314 can extend around the cavity opening 313. The cavity gasket 314 can be configured to seal with the cap cover 280 to enclose and seal the cavity 310.

The circumferential wall 312 can define external scallops 316 a,b. The external scallops 316 a,b can extend radially inward into the circumferential wall 312 relative to the cap axis 201. Each of the external scallops 316 a,b can respectively be enclosed by an antenna cover 318 a,b, and an antenna strip 320 a,b can be enclosed within each of the external scallops 316 a,b between the respective antenna cover 318 a,b and the circumferential wall 312.

The nozzle cap 150 can comprise a battery pack 360 and a printed circuit board (“PCB”) 362, each disposed within the cavity 310. The PCB 362 can be attached to a mounting bracket 364 which can be secured within the cavity 310 by a pair of fasteners 366.

As shown, the nozzle cap 150 of the fire hydrant 110 can also comprise the vibration sensor 380 of the hydrant assembly 100, and the vibration sensor 380 can be disposed within the cavity 310. The vibration sensor 380 can define a sensor axis 301 which can be perpendicular to the cap axis 201. The vibration sensor 380 can be attached to the circumferential wall 312, and the vibration sensor 380 can extend radially inward from the circumferential wall 312 and into the cavity 310 with respect to the cap axis 201.

The battery pack 360, the PCB 362, the vibration sensor 380, and the antenna strips 320 a,b can be connected together in electrical communication. The vibration sensor 380 can be configured to detect leaks within the fluid system (not shown) by monitoring vibrations travelling up the stand pipe 198 (shown in FIG. 1) and through the fire hydrant 110 (shown in FIG. 1) when the nozzle cap 150 is mounted on the nozzle 140 a (shown in FIG. 1). Vibration patterns within the fluid system can indicate the presence of leaks within the fluid system. The vibration sensor 380 can produce voltage readings when the vibration sensor 380 experiences vibrations. These voltage readings can be processed by the PCB 362 to determine whether leaks are present, and a signal can be transmitted outwards from the nozzle cap 150 by the antenna strips 320 a,b to convey whether leaks have been identified within the fluid system.

FIG. 4 is a perspective view of one example aspect of the vibration sensor 380 of FIG. 3 wherein the vibration sensor 380 is a piezoelectric vibration sensor. Piezoelectric vibration sensors are described in greater detail in U.S. Pat. No. 9,528,903, issued Dec. 27, 2016, which is hereby incorporated by reference in its entirety.

The vibration sensor 380 can comprise a base 400, at least one piezoelectric crystal 402, and a plurality of calibration masses 406. The calibration masses 406 can be distributed circumferentially around the base 400. In the present aspect, the calibration masses 406 can be integrally formed with the base 400; however in other aspects, the calibration masses 406 can be separate components which can be attached to the base 400, such as with a glue, adhesive, mastic, epoxy, or another method such as welding, brazing, soldering, or any other attachment method for example and without limitation. In the present aspect, the calibration masses 406 can extend axially outward from each side of the base 400 with respect to the sensor axis 301. A notch 432 can be defined between each pair of adjacent calibration masses 406, and the calibration masses 406 can vibrate independently from one another.

The piezoelectric crystal 402 can be attached to the base 400, and the piezoelectric crystal 402 can be disposed radially inward from the calibration masses 406 with respect to the sensor axis 301. In some aspects, an additional piezoelectric crystal (not shown) can be attached to the opposite side of the base 400. In the present aspect, the piezoelectric crystals 402 can be bonded to the base 400 with a conductive adhesive. In other aspects, the piezoelectric crystals 402 can be attached to the base 400 through other suitable means such as double-sided tape, various glues, various coatings including elastomeric and silicon coatings among others, pure adhesives, or by a fastener.

In the present aspect, a fastener 408 can extend through the base 400 and piezoelectric crystals 402. The fastener 408 can define a threaded end 410, and a spacer 404 can be fit over the fastener 408 between the base 400 and the threaded end 410. In the present aspect, the threaded end 410 can define a first sensor end 412 of the vibration sensor 380, and a second sensor end 414 can be defined by the calibration masses 406, opposite from the first sensor end 412. The sensor axis 301 can extend through the fastener 408 and the vibration sensor 380 as a whole from the first sensor end 412 to the second sensor end 414.

The threaded end 410 can threadedly engage a threaded hole 780 (shown in FIG. 7) defined by the circumferential wall 312 (shown in FIG. 3) to attached the vibration sensor 380 to the cap body 210 (shown in FIG. 3). With the vibration sensor 380 attached to the cap body 210, and the nozzle cap 150 (shown in FIG. 3) attached to the nozzle 140 a (shown in FIG. 1), the vibration sensor 380 can detect vibrations from the fluid system (not shown) and convert the vibrations to a voltage signal. When the vibration sensor 380 is exposed to vibrations, the calibration masses 406 can oscillate axially relative to the base 400 which can produce internal stresses within the piezoelectric crystal 402. Stresses within the piezoelectric crystal 402 can produce a voltage signal which can then be interpreted by the PCB 362 (shown in FIG. 3) to determine if leaks are present within the fluid system.

FIG. 5 is a front detail view of the hydrant assembly 100 focusing on the nozzle 140 a and the nozzle cap 150 with the cap cover 280 of the nozzle cap 150 shown in transparency with the underlying components shown in dashed lines. Experimentation has revealed that the signal-to-noise ratio detected by the vibration sensor 380 is generally optimized when the sensor axis 301 is aligned with the barrel axis 101 of the barrel 120 of the fire hydrant 110, such as when vertically aligned relative to the direction of gravity as shown in the present aspect.

The cap cover 280 can define indicia 501, which can align with the circumferential placement of the vibration sensor around the circumferential wall 312. For example, in the present aspect, the vibration sensor 380 can be positioned in a six-o-clock position wherein the sensor axis 301 is vertically aligned, and the vibration sensor 380 is positioned at the bottom of the nozzle cap 150. The indicia 501 can also be positioned in the six-o-clock position so that the indicia 501 is approximately centered over the vibration sensor 380. In the present aspect, the indicia 501 can be the ECHOLOGICS logo which can be approximately centered over the vibration sensor 380; however, in other aspects, the indicia 501 can define any combination of words, numbers, and/or symbols to indicate the circumferential position of the vibration sensor 380 along the circumferential wall 312. For example, in some aspects, the indicia could be a line extending across the cap cover 280 which can be positioned parallel to the sensor axis 301 or an arrow indicating the preferred vertical alignment. Because a user cannot see into the cavity 310 in the present aspect, the indicia 501 can be configured to notify a user of the placement of the vibration sensor 380 along the circumferential wall so that the nozzle cap 150 can be optimally oriented when attaching the nozzle cap 150 to the nozzle 140 a. In other aspects, some or all of the cap cover 280 can comprise a transparent material configured to provide a view of the orientation of the vibration sensor 380 within the cavity 310.

FIG. 6 is a front detail view of the hydrant assembly 100 focusing on the nozzle 140 a and the nozzle cap 150 which demonstrates various potential positions 600 a—h for the vibration sensor 380 (shown in FIG. 5) and the sensor axis 301, as shown by the dashed lines in the shape of the vibration sensor 380. The cap cover 280 is shown without the indicia 501 (shown in FIG. 5) for clarity. The exemplary potential orientations for the sensor axis 301 are shown as 301 a—d.

Sensor axis 301 a can correspond to the vertical orientations of the twelve-o-clock position 600 a and the six-o-clock position 600 e. In these positions, the sensor axis 301 a is vertically aligned in parallel to the barrel axis 101 of the fire hydrant 110. These positions generally provide an optimal signal-to-noise ratio, as described above. In these positions, an angle defined between the sensor axis 301 a and the barrel axis 101 can equal zero degrees, and therefore, this angle is not shown or labelled.

Sensor axis 301 c corresponds to the horizontal orientations of the three-o-clock position 600 c and the nine-o-clock position 600 g. In these positions, the sensor axis 301 c is horizontally aligned, and the sensor axis 301 c can be perpendicular to the barrel axis 101. An angle A_(c) defined between the sensor axis 301 c and the barrel axis 101 can equal ninety degrees. Experimentation generally shows that the signal-to-noise ratio is least desirable when the vibration sensor 380 (shown in FIG. 5) is in a horizontal orientation with the sensor axis 301 c perpendicular to the barrel axis 101, which is vertical.

The sensor axis 301 b corresponds to the positions 600 b,f, and the sensor axis 301 d corresponds to the positions 600 d,h. The sensor axes 301 b,d can be oblique to the barrel axis 101. The sensor axis 301 b can define an angle A_(b) with the barrel axis 101, and the sensor axis 301 d can define an angle A_(d). In these positions, the angles A_(b),A_(d) can be acute angles measuring less than ninety degrees. In these aspects, the signal-to-noise ratio is generally superior to that of the horizontal orientations of positions 600 c,g but generally inferior to the signal-to-noise ratio of the vertical orientations of positions 600 a,e. The signal-to-noise ratio improves as the angles A_(b),A_(d) decrease to zero degrees, wherein the sensor axes 301 b,d align with the barrel axis 101.

The demonstrated positions 600 a—h are merely exemplary and should not be viewed as limiting. The vibration sensor 380 (shown in FIG. 5) can be oriented at any angle around the cap axis 201, shown extending out of the page. The sensor axis 301 can be perpendicular to the cap axis 201 regardless of potential orientation or rotational indexing of the nozzle cap 150.

Rotational indexing of the nozzle cap 150 relative to the nozzle 140 a can be primarily dictated by the torque required to form a seal between the nozzle cap 150 and the nozzle 140 a via the gasket 222 (shown in FIG. 2). For example, in an aspect wherein the internal threading 218 (shown in FIG. 2) of the threaded bore 216 (shown in FIG. 2) is right-handed threading, the nozzle cap 150 can be tightened onto the nozzle 140 a by rotating the nozzle cap 150 in a clockwise direction about the cap axis 201 relative to the viewing angle shown. For example, in some aspects, the torque required to form a seal may naturally place the vibration sensor 380 (shown in FIG. 5) in one of the less desirable positions, such as position 600 c. In such a case, if the nozzle cap 150 is backed off to place the vibration sensor 380 in the desirable twelve-o-clock position 600 a, the seal between the nozzle cap 150 and the nozzle 140 a may be compromised, and the nozzle cap 150 can leak. Conversely, a user can attempt to overtighten the nozzle cap 150 towards the desirable six-o-clock position 600 e; however, the user may not be able to fully rotate the nozzle cap 150 to vertically align the vibration sensor 380 and achieve optimal signal-to-noise ratio. Additionally, overtightening the nozzle cap 150 can make the nozzle cap 150 difficult to remove, such as in the case of an emergency where firemen may need to open the nozzle 140 a.

One solution is to alter a gasket thickness T (shown in FIG. 7) of the gasket 222 (shown in FIG. 7) to adjust the rotational indexing of the nozzle cap 150 relative to the nozzle 140 a. By increasing the gasket thickness T of the gasket 222, the rotational indexing of the nozzle cap 150 can be rotated counter-clockwise about the cap axis 201 with respect to the viewing angle shown in aspects wherein the internal threading 218 (shown in FIG. 2) is right-handed threading. For example, if the vibration sensor 380 (shown in FIG. 7) is in position 600 b when the nozzle cap 150 is torqued to the required specification to seal the nozzle 140 a, the nozzle cap 150 can be removed, and the gasket 222 can be replaced with another gasket 222 having a larger gasket thickness T so that the vibration sensor 380 can be placed in the twelve-o-clock position 600 a when the nozzle cap 150 is torqued to the required specification.

Conversely, a thinner gasket 222 can be used to rotate the rotational indexing of the nozzle cap 150 in the clockwise direction about the cap axis 201 with respect to the viewing angle shown. For example, if the vibration sensor 380 is in position 600 d when the nozzle cap 150 is torqued to the required specification to seal the nozzle 140 a, the nozzle cap 150 can be removed, and the gasket 222 can be replaced with another gasket 222 having a smaller gasket thickness T so that the vibration sensor 380 can be placed in the six-o-clock position 600 e when the nozzle cap 150 is torqued to the required specification.

Rather than changing the gasket thickness T of the gasket 222, similar results can be achieved by positioning shims between the gasket 222 and the inner wall 220 (shown in FIG. 2), and a pack of shims of varying thicknesses can be included with an installation kit for the nozzle cap 150. In some aspects, the shim could be attached to the inner wall 220 with an adhesive sealant to prevent leaks between the shim and the inner wall 220. In other aspects, two gaskets 222 can be utilized, and the shim can be positioned between the two gaskets 222 to prevent leaks between the shim and the inner wall 220. The necessary thickness of the shims can be calculated based on the thread pitch of the internal threading 218 (shown in FIG. 2) using the following formula:

${\frac{\theta}{360 \times {TPI}} = {{Shim}\mspace{14mu}{Thickness}\mspace{14mu}{or}\mspace{14mu}{Change}\mspace{14mu}{in}\mspace{14mu}{Gasket}\mspace{14mu}{Thickness}\mspace{14mu} T}};$

wherein θ equals the desired angle of rotational correction in degrees, TPI is the threads-per-inch pitch of the internal threading 218, and shim thickness is measured in inches. For example and without limitation, if the internal threading 218 defines a thread pitch of 5 TPI, then each clockwise 360-degree rotation of the nozzle cap 150 translates the nozzle cap 150 0.20″ along the cap axis 201 towards the nozzle 140 a. In order to alter the rotational indexing of the nozzle cap 150 counterclockwise by ninety degrees, a 0.05″ shim can be added between the gasket 222 and the inner wall 220. The same formula can be utilized to determine the necessary increase or decrease in gasket thickness T (shown in FIG. 7) to achieve the desired rotational indexing of the nozzle cap 150.

In some aspects of the nozzle cap 150, two vibration sensors 380 can be attached to the nozzle cap 150 at a ninety-degree offset from one another along the circumferential wall 312 (shown in FIG. 3). In such an aspect, the nozzle cap 150 would only have to be overtightened or backed off by a maximum of forty-five degrees to position one of the two vibration sensors 380 in one of the vertical orientations: the twelve-o-clock position 600 a or the six-o-clock position 600 e. In such aspects, the nozzle cap 150 can comprise an accelerometer to determine which of the two vibration sensors 380 is more optimally oriented when taking readings. In some aspects, the gasket 222 can comprise a soft, compressive material, such as a soft rubber like neoprene, which can allow for a greater range of adjustment to the rotational indexing compared to a harder material, such as a hard rubber.

FIG. 7 is a cross-sectional side view of the barrel 120 and nozzle cap 150 of FIG. 1 taken along line 7-7 shown in FIG. 6. In the aspect shown, the vibration sensor 380 can be in the six-o-clock position, and the sensor axis 301 can be vertically aligned in parallel with the barrel axis 101. Each of the barrel axis 101 and the sensor axis 301 can be perpendicular to the cap axis 201.

As shown and previously described, the gasket 222 can define the gasket thickness T, and the gasket 222 can be positioned between the inner wall 220 of the cap body 210 and a nozzle end 740 of the nozzle 140 a. The vibration sensor 380 can also be screwed into the threaded hole 780 defined by the circumferential wall 312 to secure the vibration sensor 380 to the circumferential wall 312.

In other aspects, the vibration sensor 380 can be positioned within the bonnet 180 (shown in FIG. 1) of the fire hydrant 110 (shown in FIG. 1) or within the barrel 120 (shown in FIG. 1) of the fire hydrant 110. In such an aspect, the sensor axis 301 can be vertically aligned parallel with the barrel axis 101 of the barrel 120. Improvement in the signal-to-noise ratio for the vibration sensor 380 can be attributed to aligning the direction of oscillation of the calibration masses 406 (shown in FIG. 4) with the direction of vibration propagation. The calibration masses 406 can oscillate substantially axially along the sensor axis 301 of the vibration sensor 380. The vibrations can originate within the fluid system and then travel substantially vertically up the stand pipe 198 (shown in FIG. 1) to the fire hydrant 110. By vertically aligning the sensor axis 301 parallel to the barrel axis 101, the calibration masses 406 can be ideally positioned to oscillate upwards and downwards, which makes the vibration sensor 380 more sensitive to the vibrations propagating up the stand pipe 198 to the fire hydrant 110.

During experimentation, vibration sensors were installed on a fire hydrant attached to a 6-inch ductile iron water main at a test facility. Vibration sensors were positioned in both vertical and horizontal orientations, and the vibration sensors took readings while water was flowed from valves to simulate leaks in the water main. Across the frequency range 0-1200 Hz, the vertically oriented sensor demonstrated an average 3 dB increase in signal strength relative to the horizontally oriented sensor. Further testing was conducted wherein individuals clapped and yelled in proximity to the fire hydrant to measure sensitivity to airborne background noise, and the vibration sensors in the vertical orientation were found to be less sensitive to background noise. Across the frequency range 0-1200 Hz, the vertically oriented sensor demonstrated an average 8 dB increase in signal-to-noise ratio when comparing the leak simulation to airborne noise.

Further testing was conducted with fire hydrants to determine if the increase in signal-to-noise ratio would offer improved performance in detecting leaks. Vibration sensors in both horizontal and vertical orientations were attached to two separate fire hydrants while leaks of varying sizes were simulated by opening valves in the attached water infrastructure systems. In sixteen out of seventeen conditions tested, the vertically oriented sensors yielded correlations of higher strength than the horizontally oriented sensors, which demonstrates a higher likelihood that the vertically oriented sensors would detect the leak in a real world scenario.

One should note that conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more particular embodiments or that one or more particular embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment.

It should be emphasized that the above-described embodiments are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present disclosure. Any process descriptions or blocks in flow diagrams should be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps in the process, and alternate implementations are included in which functions may not be included or executed at all, may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present disclosure. Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the present disclosure. Further, the scope of the present disclosure is intended to cover any and all combinations and sub-combinations of all elements, features, and aspects discussed above. All such modifications and variations are intended to be included herein within the scope of the present disclosure, and all possible claims to individual aspects or combinations of elements or steps are intended to be supported by the present disclosure. 

That which is claimed is:
 1. A nozzle cap comprising: a cap body defining a cap axis, the cap body defining a circumferential wall extending circumferentially around the cap axis; and a vibration sensor comprising a shaft, the shaft defining a first end and a second end, the first end attached to the circumferential wall, the cap axis positioned closer to the second end than to the first end.
 2. The nozzle cap of claim 1, wherein the shaft is defined by a fastener of the vibration sensor.
 3. The nozzle cap of claim 2, wherein the first end is a threaded end.
 4. The nozzle cap of claim 1, wherein the vibration sensor further comprises at least one piezoelectric crystal positioned adjacent to the second end.
 5. The nozzle cap of claim 1, wherein the vibration sensor further comprises at least one calibration mass positioned adjacent to the second end.
 6. The nozzle cap of claim 1, wherein a spacer is positioned between the first end and the second end.
 7. The nozzle cap of claim 1, wherein the shaft defines a sensor axis extending from the first end to the second end, and wherein the sensor axis extends radially inward with respect to the cap axis.
 8. The nozzle cap of claim 7, wherein the sensor axis is perpendicular to the cap axis.
 9. The nozzle cap of claim 1, wherein the circumferential wall defines a cavity, wherein the nozzle cap further comprises a printed circuit board positioned in the cavity, and wherein the printed circuit board is connected in electrical communication with the vibration sensor and an antenna.
 10. A hydrant assembly comprising: a fire hydrant comprising a barrel and a nozzle extending outwards from the barrel; and a nozzle cap comprising: a cap body mounted on the nozzle, the cap body defining a cap axis, the cap body defining a circumferential wall extending circumferentially around the cap axis; and a vibration sensor comprising a shaft, the shaft defining a first end and a second end, the first end attached to the circumferential wall, the cap axis positioned closer to the second end than to the first end.
 11. The hydrant assembly of claim 10, wherein the shaft is defined by a fastener of the vibration sensor.
 12. The hydrant assembly of claim 11, wherein the first end is a threaded end.
 13. The hydrant assembly of claim 10, wherein the vibration sensor further comprises at least one piezoelectric crystal positioned adjacent to the second end.
 14. The hydrant assembly of claim 10, wherein the vibration sensor further comprises at least one calibration mass positioned adjacent to the second end.
 15. The hydrant assembly of claim 10, wherein a spacer is positioned between the first end and the second end.
 16. The hydrant assembly of claim 10, wherein the shaft defines a sensor axis extending from the first end to the second end, and wherein the sensor axis extends radially inward with respect to the cap axis.
 17. The hydrant assembly of claim 16, wherein the sensor axis is perpendicular to the cap axis.
 18. The hydrant assembly of claim 10, wherein the circumferential wall defines a cavity, wherein the nozzle cap further comprises a printed circuit board positioned in the cavity, and wherein the printed circuit board is connected in electrical communication with the vibration sensor and an antenna. 